[libav-bugs] [Bug 515] implement runtime CPU detection for SPARC VIS accelerations

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Wed May 22 16:07:53 CEST 2013


https://bugzilla.libav.org/show_bug.cgi?id=515

--- Comment #10 from Michael Kostylev <michael.kostylev at gmail.com> 2013-05-22 16:07:53 CEST ---
> ARM accelerations are reading /proc/self/auxv, which may help us as well. Let's
> make this code available for other architectures as at least the reading part
> is only specific to Linux.

There is nothing about VIS there, since a corresponding HWCAP_SPARC_ is missing
(linux-3.9). Just for completeness, /proc/self/auxv:
US-II   00 00 00 10 00 00 00 1F
US T1   00 00 00 10 00 00 8B 5F

Now compare with /proc/cpuinfo:
US-II   cpucaps : flush,stbar,swap,muldiv,v9,mul32,div32,v8plus,vis
US T1   cpucaps :
flush,stbar,swap,muldiv,v9,blkinit,mul32,div32,v8plus,ASIBlkInit

Parsing /proc/cpuinfo would be ok, a minor disadvantage is that the cpucaps are
a relatively new feature.

> Not sure what to do about Solaris or the BSDs with SPARC ports, though.

I did not look at NetBSD yet, but OpenBSD does not expose anything. They even
made reading the tick counter a privileled operation. So, I'd leave SIGILL
handling as a last resort.

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